A hollow-fiber membrane module packed with hollow fiber membranes is widely used for the purpose of separating and filtering proteins, viruses, and contaminants in a cell suspension in blood purification or plasma skimming in the field of extracorporeal circulation, or in the field of cell therapy. In a case where a hollow-fiber membrane module is used in the field of extracorporeal circulation, since the blood that has passed through the hollow-fiber membrane module returns directly into the body, it is required to completely remove the air and air bubbles filled in the hollow-fiber membrane module in advance, and “priming” for introducing a priming liquid such as physiological saline into the hollow-fiber membrane module is performed before starting the extracorporeal circulation (Patent Literature 1). However, in order to fill the whole hollow-fiber membrane module with priming liquid, the priming liquid is introduced from the inside and the outside of the hollow fiber membrane, that is, from both the blood channel side and the dialysate side by the different flow paths, therefore, in the process, the switching of the flow paths is complicated and takes a long time.
On the other hand, the priming method in the case of using the hollow-fiber membrane module in the field of cell therapy has not been considered at all (Patent Literature 2). This is because in the field of cell therapy, being different from extracorporeal circulation, the cell suspension that has passed through the hollow-fiber membrane module does not return directly into the body, therefore, it is not required to completely remove the air and air bubbles in the hollow-fiber membrane module in advance, and it is considered that the necessity of the consideration for performing the priming was low. However, in order to efficiently separate and filter proteins, viruses, and contaminants in the cell suspension, it is required to treat the cells in a state that both the inside and the outside of the hollow fiber membrane are wet, therefore, the process of the “priming” in which the inside and the outside of the hollow fiber membrane are filled with a priming liquid, such as physiological saline, before starting the treatment of cells, and the effective filtration area of the hollow fiber membrane is enlarged, contributes to the improvement of the filtration rate and the improvement of the cell recovery rate, and therefore, is extremely important. Further, in a case where the hollow-fiber membrane module is used in cell therapy applications, being different from blood purification, it is difficult to assume that the priming liquid is introduced from the outside of the hollow fiber membrane, but from the viewpoint of bringing the priming liquid into contact with the hollow fiber membrane rapidly, there were some cases where the priming liquid is introduced from the outside of the hollow fiber membrane through a large-diameter opening. Accordingly, also in the cell therapy applications, a priming method in which the priming liquid introduced from the inside of the hollow fiber membrane can be filled into both the inside and the outside of the hollow fiber membrane is required, but as described above, such a method has not been considered at all in the past, and in order to realize this, there was no choice but to devise the structure of the hollow-fiber membrane module, for example, an air release valve is provided in the outside of the hollow fiber membrane, and the air existing in the outside of the hollow fiber membrane is released.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2009-268762
Patent Document 2: PCT International Publication No. 2013/061859